In a broadcasting station, production studio or the like for preparing television broadcasting programs or video software, or the like, it is generally desirable to selectively choose video signals or audio signals to be fed to, or transmitted from, one of a plurality of devices such as a video tape recorder (VTR), video disc recording/reproducing apparatus, audio tape recorder, audio disc recording/reproducing apparatus, microphone or television camera, or the like.
For example, a matrix switcher apparatus having switches arranged in a matrix configuration is generally provided between some edit rooms and a VTR room in which a plurality of VTRs or various recording/reproducing apparatuses or the like are concentrically arranged. When the switches in the matrix switcher apparatus are arbitrarily changed to designate one of the edit rooms and a desired device, such as the VTRs arranged in the VTR room, the designated device and the designated edit room are connected through the matrix switcher apparatus.
The thus constituted matrix switcher apparatus differs in its required matrix scale depending on the number of devices being used and the number of the edit rooms or the like. Further, the matrix switcher apparatus sometimes deals with different types of input and output signals such as digital serial signals and analog signals, and further sometimes deals with more than ten channels of various signals. In these cases, since it is difficult to perform the switching operations of the system by one matrix switcher apparatus due to the number, and varying type of signal, there has been proposed that a plurality of matrix switcher units of small or intermediate scales each capable of dealing with signals of channels are provided to constitute a matrix switcher apparatus which can deal with a plurality of various types of signals.
An example of a conventional matrix switcher apparatus which is arranged to change over digital serial signals and analog signals will be explained with reference to FIG. 1. This matrix switcher apparatus is used in an electronic edit system so as to selectively change connection between VTRs (VTR1-VTR10) for reproduction in a VTR room and edit rooms 1-3 having VTRs (VTR11-VTR13) for recording, respectively.
Each of the VTRs (VTR1-VTR10) shown in FIG. 1 receives and outputs a digital serial signal, such as a video signal or an audio signal, and an analog signal, such as a video signal or an audio signal. Matrix switcher units MSU1 and MSU2 used in the apparatus are provided depending on respective signal types. Each of the edit rooms 1 and 2 deals with both the digital serial signal and the analog signal, whereas the edit room 3 deals with only the analog signal. Each of the VTRs (VTR1-VTR10) in each of the VTR rooms is shared by the VTRs (VTR11-VTR13) in the edit rooms 1 to 3.
The apparatus is arranged in a manner that if the edit room 1 selects a digital serial signal of the VTR1 through the matrix switcher unit MSU1 for a digital serial signal, for example, the edit room 1 also selects an analog signal of the VTR1 through the matrix switcher unit MSU2 for an analog signal. In contrast, the edit room 3 can select signals of the VTRs in the VTR room only through the matrix switcher unit MSU2.
With reference to the system shown in FIG. 1, it can be seen that in the general matrix switcher apparatus a remote control unit, or remote controller, is provided to selectively turn on and off each of the cross point switches so that a desired input or output signal path is selected. That is, a desired signal routing is accomplished by manipulating buttons or levers, or the like, provided on an operation or control panel of the remote controller. In the above-described matrix switcher apparatus having a plurality of matrix switcher units, such as MSU1 and MSU2, there is also a plurality of remote controllers such as RCD and RCA provided in correspondence to the matrix switcher units, respectively. In this case, protocols and transmission formats or the like are required to be suitably set in order to transmit control signals or the like between the matrix switcher units MSU1 and MSU2 and the remote controllers RCD and RCA, respectively.
From the standpoint of this requirement, S-BUS has been proposed as a transmission standard. Details of S-BUS will be described later. A matrix switcher apparatus in compliance with this standard includes a plurality of matrix switcher units each having a matrix switcher for selectively connecting input channels and output channels, a control circuit for turning on and off each switch of the matrix switcher, and a transmitter/receiver circuit for transmitting and receiving communication data, including data related to the control operation of the control circuit through an external serial bus line. The matrix switcher apparatus, in compliance with the S-BUS standard, further includes at least one remote control unit having a transmitter/receiver circuit and a control circuit for remotely controlling these matrix switcher units, so that the communication data is transmitted through the external serial bus lines between each of the transmitter/receiver circuits of the matrix switcher circuits and the transmitting/receiving circuit of the remote control unit. Each of the remote control units is constituted so as to be selectively set to be either a primary station or a secondary station. The remote control units are set in a manner that only one unit is set to be the primary station and the remaining units are set to be the secondary stations. The primary station sequentially polls, or scans all of the remote control units to request transmission of data, then stores communication data output from those remote control units having data to be transmitted. The stored communication data is then collectively transmitted. Each of the units receives only data associated with its own unit from among the communication data transmitted from the primary station.
At present, only some currently known matrix switcher apparatuses operate on the above-described transmission standard (S-BUS). In the matrix switcher apparatus described in FIG. 1, the matrix switcher unit MSU1 employs the above-described transmission standard for a digital serial signal, while the matrix switcher unit MSU2 employs different serial transmission standard for an analog signal. Thus, the matrix switcher apparatus in FIG. 1 employs the remote controllers RCD and RCA for the respective transmission standards to thereby selectively change the matrix switcher units MSU1 and MSU2.
Accordingly, when a plurality of matrix switcher units are controlled through communication means in compliance with different transmission standards different remote control units are required to accommodate the different transmission standards. As a result, the operations of the apparatus is more complicated.